Previously, a liquid pump, which rotates a rotatable member, such an impeller, by a motor arrangement received in an inside of the liquid pump to pump liquid, is known. In general, in the liquid pump having the above-described motor arrangement, the liquid, which is drawn through a suction port formed at one axial end of the liquid pump, is pressurized and is discharged to an outside through a discharge port formed at the other axial end of the liquid pump.
A discharge conduit, which forms the discharge port, is formed integrally with a cover end made of resin in such a manner that the discharge conduit projects from the axial end portion of the liquid pump. A tubular portion, which holds a bearing that rotatably supports one end portion of a shaft of the motor arrangement, is formed in an inside of the cover end along a central axis of the cover end. Furthermore, an end portion of a stator of the motor arrangement, specifically, a stator winding portion, and winding connections for connecting with windings are molded with resin for the purpose of electrical insulation.
For example, in a fuel supply pump recited in the Patent Literature 1, the winding portion, a dielectric molded portion of the winding portion, and the cover end located at the discharge port side end portion of the fuel supply pump in the axial direction are formed integrally with the resin. Communication passages, each of which communicates between a radially inner side of the cover end and a radially outer side of the cover end, are formed. The fuel, which is pumped from the pump arrangement, flows from a second fuel supply passage, which is formed between an outer peripheral portion of the stator core and an inner peripheral portion of a housing, into a fuel merging portion located on the radially inner side through the communication passages.
In the construction of the Patent Literature 1, circumferential portions of the cover end, which are other than the communication passages, become thick wall portions made of the molded resin. In general, the thick wall portion accumulates the greater amount of heat in comparison to a thin wall portion at the time of resin molding to cause generation of a sink mark and/or deformation due to localized shrinkage of the resin material. Particularly, when the sink mark and/or the deformation is formed in the tubular portion, which holds the bearing that rotatably supports the one end portion of the shaft, it will cause deviation of the central axis of the shaft or tilt of the central axis of the shaft at the time of installing the shaft. Thereby, required axis accuracy of the shaft, such as required coaxiality or required perpendicularity of the shaft, cannot be ensured. As a result, the operational performance or the durability of the motor arrangement may possibly be adversely influenced.